[FDS] hot melt fastening technology, a new height in the domestic automobile industry

In the new energy era, the lightweight of automobile has been paid more and more attention. According to the report of the world automobile association, for every 10% reduction in vehicle weight, fuel consumption can be reduced by 6% - 8%. The lightweight of the vehicle contributes to the fuel economy and improves the stability of vehicle control. However, in order to improve the performance of the car, we have to equip the car with more equipment. Therefore, if we want to realize the lightweight of the car body, we must minimize the weight of the car body materials. However, the application of new materials challenges the traditional connection methods.

At present, there are more than ten connection modes of automobile lightweight aluminum and iron, and the most frequently used are FDS process, SPR process and resistance spot welding RSW. However, SPR process is a robust and replaceable technology, which requires a variety of rivet and rivet die combinations, and the equipment cost is expensive; Although the technology of RSW is mature, it is limited and cannot be connected to heterogeneous gold bodies. FDS process can not only connect one side, but also connect various heterogeneous materials, which can effectively solve bilateral problems. Let's briefly understand the FDS process.

FDS (flow drill screw) flow drill screw, namely automatic bolt tightening technology. FDS screw is mainly composed of six parts (as shown in the figure below), screw head, load thread, thread forming area, cylindrical area, drilling area and screw tip.

FDS fastening process includes six steps: rotation → perforation → through hole → tapping → screwing → fastening. The high-speed rotating motor transmits the rotating power to the flow drill screw. The friction between the screw tip and the base metal surface produces high temperature, which makes the base metal soften and enter the perforation stage. When the screw tip penetrates the base metal, most of the hot-melt base metal will flow to the lower part of the drilling hole to form a metal bushing, and the inner surface of the bushing will form meshing threads under the action of FDS screw threads. Then tighten according to the preset torque to connect two or more base metals together. FDS screw can effectively improve the reliability, anti loosening ability and fatigue strength of threaded connection.

At present, FDS hot melt self tapping screws are mainly imported. Domestic fastener manufacturers have not been able to provide this technology for the time being. We still know little about FDS screws. In the future, FDS hot melt self tapping and tightening technology will become more and more important in the field of sheet metal connection such as automobiles. We must strengthen our study and understanding of it. It is reported that Mercedes Benz, Audi and GM have widely used FDS screws on several high-end models under their respective brands, and more car companies will adopt this technology in the future.